1. Field of the Invention
The present invention relates to a liquid discharging apparatus in which a liquid discharging head is joined to a support member, and to a production method for the liquid discharging apparatus.
2. Description of the Related Art
Liquid discharging apparatuses are widely adopted as recording apparatuses for printers, copying machines, facsimile machines, word processors, etc.
A liquid discharging apparatus includes a liquid discharging head (hereinafter sometimes simply referred to as a head) which discharges liquid.
A head using electrothermal transducers typically includes nozzles having discharging ports for discharging liquid, and flow passages and a common liquid chamber for supplying the liquid to the nozzles.
There are a removable head that is removably attached to a separate liquid storage portion, and a cartridge type head combined with a liquid storage portion.
FIG. 7 is a schematic perspective view of a head cartridge of the related art. In the head cartridge, a head 702 having an element substrate and a liquid storage portion 701 for storing liquid are combined.
The head 702 is joined to a support portion 704 of the liquid storage portion 701. The head cartridge also includes a wiring board 703 having lines for transmitting electric signals from a liquid discharging apparatus body to the head.
FIG. 8 is a cross-sectional view, taken along line VIII-VIII in FIG. 7. In FIG. 8, only the support portion 704 of the liquid storage portion 701 is shown, and only the element substrate of the head 702 is shown briefly.
The support portion 704 includes a liquid supply passage 801 for supplying liquid stored in the liquid storage portion 701 to the head 702. To produce such a liquid discharging apparatus having the head cartridge, it is necessary to join the head 702 and the support portion 704.
The head 702 and the support portion 704 are typically joined with an adhesive. More specifically, after a thermosetting adhesive 802 is applied onto the support portion 704, the head 702 is positioned accurately.
In this method, it is necessary to accurately hold the head 702 relative to the support portion 704 until the adhesive 802 sets completely. To facilitate the management, the head 702 and the support portion 704 are sometimes temporarily fixed before the thermosetting adhesive 802 sets completely.
Temporary fixing is carried out by locally applying an ultraviolet curing resin 803 for temporal fixing and irradiating the ultraviolet curing resin 803 with ultraviolet rays. Subsequently, the thermosetting adhesive 802 is cured by heat.
A sealing portion 804 formed of, for example, resin, is provided between the outer periphery of the head 702 and the support portion 704. One reason for sealing is to protect an outer wall surface of the head 702 from liquid. The sealing portion 804 is generally formed of thermosetting resin that can be handled easily.
The support portion 704 also fixes the wiring board 703. The wiring board 703 is bonded and fixed to the support portion 704 with an adhesive.
The above-described method for joining the element substrate and the support portion with an adhesive is generally known. Japanese Patent Laid-Open Nos. 5-220956 and 9-183229 disclose methods in which temporary fixing is performed during joining.
Japanese Patent Laid-Open No. 5-220956 discloses that an adhesive for fixing and an adhesive for temporary fixing are used in combination. A room-temperature setting adhesive is used as the adhesive for fixing, and a fast setting adhesive is used as the adhesive for temporary fixing.
Japanese Patent Laid-Open No. 9-183229 discloses that a light curing adhesive for temporary fixing is used as a first adhesive and a natural setting or thermosetting adhesive is used as a second adhesive.
This publication also discloses that hot plate welding is used to join two resin members in a liquid storage portion. Hot plate welding is generally known as a method for welding thermoplastic resin materials.
In hot plate welding, a hot plate is placed between resin members to be joined. After the resin members are softened by heat of the hot plate, the hot plate is removed. Subsequently, the softened resin members are joined.
When the head and the support portion are joined with an adhesive, as in Japanese Patent Laid-Open No. 5-220956, part of the adhesive sometimes flows into a flow passage. This sometimes lowers the discharging performance of the head, and reduces reliability. Moreover, when the flow passage is completely blocked, discharging sometimes becomes impossible.
Further, it is necessary to apply the adhesive for temporary fixing into a small space between the outer periphery of the head and the support portion during temporary fixing. For this reason, it is difficult to adjust the position where the adhesive is applied, and the yield may decrease. Further, to increase the accuracy of the position where the adhesive is applied, an application device is complicated and an application method becomes troublesome. Therefore, the production cost may be increased.
In addition, when the adhesive spatters and adheres to the surface of the head, the discharging performance, yield, and reliability are sometimes reduced.